I have a Stihl BR420, the engine siezed the other day doing a leaf clean up. I haven't disassembled it yet, but the starter rope won't pull. Also, the engine smelled like it was really hot right before it shut down. Also, it was down on power as well. I was not the one running it, it was one of my employees. We run Stihl 2-cycle oil (50:1) mixed with 87 octane fuel. It is about 2 1/2 years old. It has some use on it, but I think it is definitely a premature failure. I would guess that it has about 250 to 500 hours on it. I would think that this engine should have gone for at least 1500 - 2500 hours. Maybe I'm a little too optimistic on that assumption. Anyway, I'm planning on tearing it down on Thanksgiving day to see whats up. I priced out a new cylinder, piston & ring, and gaskets at around $250. A new unit will cost me about $400. I would like to rebuild it since the rest of it is in good operating condition still, but I am trying to figure out why it siezed (if in fact that is what happened). Perhaps we were not doing maintenance often enough? We do do maintenance but it is possible that it was overdue. We also noticed that recently it has been hard to start (but had good compression according to the starter rope test). Is it possible that the carb is out of adjustment or plugged up (thereby leaning the mix and causing the engine failure). I know the air filter could be choked up, but that should make the mix richer, not leaner - which would cause the opposite kind of problems. Any Thoughts?